Sotiris Gourbatsis, S. Perlepes, I. Butler
Jul 30, 1999
Citations
0
Influential Citations
39
Citations
Journal
Polyhedron
Abstract
Abstract The reactions of ZnX2 (X=Cl, Br) with the di-Schiff-base ligand N,N′-bis[1-(pyridin-2-yl)ethylidene]ethane-1,2-diamine (LA) were studied. The chemical identity of the products is solvent-dependent. The reactions in tetrahydrofuran give complexes [ZnLACl2] (1) and [ZnLABr2] (2). Treatment of LA with an equimolar, or excess, amount of ZnX2 in ethanol yields the five-coordinate complexes [ZnLCl2] (3) and [ZnLBr2] (4), where L is the mono-Schiff base N-[1-pyridin-2-yl)ethylidene]-ethane-1,2-diamine; complexes 3 and 4 have resulted from hydrolytic cleavage of the precursor di-Schiff base LA. These two complexes can also be prepared in one step and in good yield by the reactions of ZnX2 with 2-acetylpyridine and ethane-1,2-diamine in refluxing methanol. The X-ray structure of 3 demonstrates that L behaves as a tridentate chelate with the ligated atoms being the pyridine, methine and amino nitrogens; two terminal, equatorial chlorides complete five-coordination at zinc(II). The new complexes 1–4 were characterized by elemental analyses and spectroscopic (IR, far-IR, 1H NMR) techniques. It is proposed that LA behaves as a tetradentate chelate in complexes 1 and 2, for which a monomeric pseudo-octahedral stereochemistry with trans chloro ligands is assigned in the solid state. All data are discussed in terms of the nature of bonding and known or assigned structures.